package com.sunyard.utils.sm2;

import org.bouncycastle.crypto.BlockCipher;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.DataLengthException;
import org.bouncycastle.crypto.OutputLengthException;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.util.Pack;

/**
 * SM4 Block Cipher - SM4 is a 128 bit block cipher with a 128 bit key.
 * <p>
 * The implementation here is based on the document <a
 * href="http://eprint.iacr.org/2008/329.pdf"
 * >http://eprint.iacr.org/2008/329.pdf</a> by Whitfield Diffie and George
 * Ledin, which is a translation of Prof. LU Shu-wang's original standard.
 * </p>
 */
public class SM4Engine implements BlockCipher {
    private static final int BLOCK_SIZE = 16;

    private final static byte[] Sbox = {(byte) 0xd6, (byte) 0x90, (byte) 0xe9,
            (byte) 0xfe, (byte) 0xcc, (byte) 0xe1, (byte) 0x3d, (byte) 0xb7,
            (byte) 0x16, (byte) 0xb6, (byte) 0x14, (byte) 0xc2, (byte) 0x28,
            (byte) 0xfb, (byte) 0x2c, (byte) 0x05, (byte) 0x2b, (byte) 0x67,
            (byte) 0x9a, (byte) 0x76, (byte) 0x2a, (byte) 0xbe, (byte) 0x04,
            (byte) 0xc3, (byte) 0xaa, (byte) 0x44, (byte) 0x13, (byte) 0x26,
            (byte) 0x49, (byte) 0x86, (byte) 0x06, (byte) 0x99, (byte) 0x9c,
            (byte) 0x42, (byte) 0x50, (byte) 0xf4, (byte) 0x91, (byte) 0xef,
            (byte) 0x98, (byte) 0x7a, (byte) 0x33, (byte) 0x54, (byte) 0x0b,
            (byte) 0x43, (byte) 0xed, (byte) 0xcf, (byte) 0xac, (byte) 0x62,
            (byte) 0xe4, (byte) 0xb3, (byte) 0x1c, (byte) 0xa9, (byte) 0xc9,
            (byte) 0x08, (byte) 0xe8, (byte) 0x95, (byte) 0x80, (byte) 0xdf,
            (byte) 0x94, (byte) 0xfa, (byte) 0x75, (byte) 0x8f, (byte) 0x3f,
            (byte) 0xa6, (byte) 0x47, (byte) 0x07, (byte) 0xa7, (byte) 0xfc,
            (byte) 0xf3, (byte) 0x73, (byte) 0x17, (byte) 0xba, (byte) 0x83,
            (byte) 0x59, (byte) 0x3c, (byte) 0x19, (byte) 0xe6, (byte) 0x85,
            (byte) 0x4f, (byte) 0xa8, (byte) 0x68, (byte) 0x6b, (byte) 0x81,
            (byte) 0xb2, (byte) 0x71, (byte) 0x64, (byte) 0xda, (byte) 0x8b,
            (byte) 0xf8, (byte) 0xeb, (byte) 0x0f, (byte) 0x4b, (byte) 0x70,
            (byte) 0x56, (byte) 0x9d, (byte) 0x35, (byte) 0x1e, (byte) 0x24,
            (byte) 0x0e, (byte) 0x5e, (byte) 0x63, (byte) 0x58, (byte) 0xd1,
            (byte) 0xa2, (byte) 0x25, (byte) 0x22, (byte) 0x7c, (byte) 0x3b,
            (byte) 0x01, (byte) 0x21, (byte) 0x78, (byte) 0x87, (byte) 0xd4,
            (byte) 0x00, (byte) 0x46, (byte) 0x57, (byte) 0x9f, (byte) 0xd3,
            (byte) 0x27, (byte) 0x52, (byte) 0x4c, (byte) 0x36, (byte) 0x02,
            (byte) 0xe7, (byte) 0xa0, (byte) 0xc4, (byte) 0xc8, (byte) 0x9e,
            (byte) 0xea, (byte) 0xbf, (byte) 0x8a, (byte) 0xd2, (byte) 0x40,
            (byte) 0xc7, (byte) 0x38, (byte) 0xb5, (byte) 0xa3, (byte) 0xf7,
            (byte) 0xf2, (byte) 0xce, (byte) 0xf9, (byte) 0x61, (byte) 0x15,
            (byte) 0xa1, (byte) 0xe0, (byte) 0xae, (byte) 0x5d, (byte) 0xa4,
            (byte) 0x9b, (byte) 0x34, (byte) 0x1a, (byte) 0x55, (byte) 0xad,
            (byte) 0x93, (byte) 0x32, (byte) 0x30, (byte) 0xf5, (byte) 0x8c,
            (byte) 0xb1, (byte) 0xe3, (byte) 0x1d, (byte) 0xf6, (byte) 0xe2,
            (byte) 0x2e, (byte) 0x82, (byte) 0x66, (byte) 0xca, (byte) 0x60,
            (byte) 0xc0, (byte) 0x29, (byte) 0x23, (byte) 0xab, (byte) 0x0d,
            (byte) 0x53, (byte) 0x4e, (byte) 0x6f, (byte) 0xd5, (byte) 0xdb,
            (byte) 0x37, (byte) 0x45, (byte) 0xde, (byte) 0xfd, (byte) 0x8e,
            (byte) 0x2f, (byte) 0x03, (byte) 0xff, (byte) 0x6a, (byte) 0x72,
            (byte) 0x6d, (byte) 0x6c, (byte) 0x5b, (byte) 0x51, (byte) 0x8d,
            (byte) 0x1b, (byte) 0xaf, (byte) 0x92, (byte) 0xbb, (byte) 0xdd,
            (byte) 0xbc, (byte) 0x7f, (byte) 0x11, (byte) 0xd9, (byte) 0x5c,
            (byte) 0x41, (byte) 0x1f, (byte) 0x10, (byte) 0x5a, (byte) 0xd8,
            (byte) 0x0a, (byte) 0xc1, (byte) 0x31, (byte) 0x88, (byte) 0xa5,
            (byte) 0xcd, (byte) 0x7b, (byte) 0xbd, (byte) 0x2d, (byte) 0x74,
            (byte) 0xd0, (byte) 0x12, (byte) 0xb8, (byte) 0xe5, (byte) 0xb4,
            (byte) 0xb0, (byte) 0x89, (byte) 0x69, (byte) 0x97, (byte) 0x4a,
            (byte) 0x0c, (byte) 0x96, (byte) 0x77, (byte) 0x7e, (byte) 0x65,
            (byte) 0xb9, (byte) 0xf1, (byte) 0x09, (byte) 0xc5, (byte) 0x6e,
            (byte) 0xc6, (byte) 0x84, (byte) 0x18, (byte) 0xf0, (byte) 0x7d,
            (byte) 0xec, (byte) 0x3a, (byte) 0xdc, (byte) 0x4d, (byte) 0x20,
            (byte) 0x79, (byte) 0xee, (byte) 0x5f, (byte) 0x3e, (byte) 0xd7,
            (byte) 0xcb, (byte) 0x39, (byte) 0x48};

    private final static int[] CK = {0x00070e15, 0x1c232a31, 0x383f464d,
            0x545b6269, 0x70777e85, 0x8c939aa1, 0xa8afb6bd, 0xc4cbd2d9,
            0xe0e7eef5, 0xfc030a11, 0x181f262d, 0x343b4249, 0x50575e65,
            0x6c737a81, 0x888f969d, 0xa4abb2b9, 0xc0c7ced5, 0xdce3eaf1,
            0xf8ff060d, 0x141b2229, 0x30373e45, 0x4c535a61, 0x686f767d,
            0x848b9299, 0xa0a7aeb5, 0xbcc3cad1, 0xd8dfe6ed, 0xf4fb0209,
            0x10171e25, 0x2c333a41, 0x484f565d, 0x646b7279};

    private final static int[] FK = {0xa3b1bac6, 0x56aa3350, 0x677d9197,
            0xb27022dc};

    private final int[] X = new int[4];

    private int[] rk;

    private int rotateLeft(int x, int bits) {
        return (x << bits) | (x >>> -bits);
    }

    // non-linear substitution tau.
    private int tau(int A) {
        int b0 = Sbox[(A >> 24) & 0xff] & 0xff;
        int b1 = Sbox[(A >> 16) & 0xff] & 0xff;
        int b2 = Sbox[(A >> 8) & 0xff] & 0xff;
        int b3 = Sbox[A & 0xff] & 0xff;

        return (b0 << 24) | (b1 << 16) | (b2 << 8) | b3;
    }

    private int L_ap(int B) {
        return (B ^ (rotateLeft(B, 13)) ^ (rotateLeft(B, 23)));
    }

    private int T_ap(int Z) {
        return L_ap(tau(Z));
    }

    // Key expansion
    private int[] expandKey(boolean forEncryption, byte[] key) {
        int[] rk = new int[32];
        int[] MK = new int[4];

        MK[0] = Pack.bigEndianToInt(key, 0);
        MK[1] = Pack.bigEndianToInt(key, 4);
        MK[2] = Pack.bigEndianToInt(key, 8);
        MK[3] = Pack.bigEndianToInt(key, 12);

        int i;
        int[] K = new int[4];
        K[0] = MK[0] ^ FK[0];
        K[1] = MK[1] ^ FK[1];
        K[2] = MK[2] ^ FK[2];
        K[3] = MK[3] ^ FK[3];

        if (forEncryption) {
            rk[0] = K[0] ^ T_ap(K[1] ^ K[2] ^ K[3] ^ CK[0]);
            rk[1] = K[1] ^ T_ap(K[2] ^ K[3] ^ rk[0] ^ CK[1]);
            rk[2] = K[2] ^ T_ap(K[3] ^ rk[0] ^ rk[1] ^ CK[2]);
            rk[3] = K[3] ^ T_ap(rk[0] ^ rk[1] ^ rk[2] ^ CK[3]);
            for (i = 4; i < 32; i++) {
                rk[i] = rk[i - 4]
                        ^ T_ap(rk[i - 3] ^ rk[i - 2] ^ rk[i - 1] ^ CK[i]);
            }
        } else {
            rk[31] = K[0] ^ T_ap(K[1] ^ K[2] ^ K[3] ^ CK[0]);
            rk[30] = K[1] ^ T_ap(K[2] ^ K[3] ^ rk[31] ^ CK[1]);
            rk[29] = K[2] ^ T_ap(K[3] ^ rk[31] ^ rk[30] ^ CK[2]);
            rk[28] = K[3] ^ T_ap(rk[31] ^ rk[30] ^ rk[29] ^ CK[3]);
            for (i = 27; i >= 0; i--) {
                rk[i] = rk[i + 4]
                        ^ T_ap(rk[i + 3] ^ rk[i + 2] ^ rk[i + 1] ^ CK[31 - i]);
            }
        }

        return rk;
    }

    // Linear substitution L
    private int L(int B) {
        int C;
        C = (B ^ (rotateLeft(B, 2)) ^ (rotateLeft(B, 10)) ^ (rotateLeft(B, 18)) ^ (rotateLeft(
                B, 24)));
        return C;
    }

    // Mixer-substitution T
    private int T(int Z) {
        return L(tau(Z));
    }

    // reverse substitution
    private void R(int[] A, int off) {
        int off0 = off;
        int off1 = off + 1;
        int off2 = off + 2;
        int off3 = off + 3;

        A[off0] = A[off0] ^ A[off3];
        A[off3] = A[off0] ^ A[off3];
        A[off0] = A[off0] ^ A[off3];
        A[off1] = A[off1] ^ A[off2];
        A[off2] = A[off1] ^ A[off2];
        A[off1] = A[off1] ^ A[off2];
    }

    // The round functions
    private int F0(int[] X, int rk) {
        return (X[0] ^ T(X[1] ^ X[2] ^ X[3] ^ rk));
    }

    private int F1(int[] X, int rk) {
        return (X[1] ^ T(X[2] ^ X[3] ^ X[0] ^ rk));
    }

    private int F2(int[] X, int rk) {
        return (X[2] ^ T(X[3] ^ X[0] ^ X[1] ^ rk));
    }

    private int F3(int[] X, int rk) {
        return (X[3] ^ T(X[0] ^ X[1] ^ X[2] ^ rk));
    }

    public void init(boolean forEncryption, CipherParameters params)
            throws IllegalArgumentException {
        if (params instanceof KeyParameter) {
            byte[] key = ((KeyParameter) params).getKey();

            if (key.length != 16) {
                throw new IllegalArgumentException("SM4 requires a 128 bit key");
            }

            rk = expandKey(forEncryption, key);
        } else {
            throw new IllegalArgumentException(
                    "invalid parameter passed to SM4 init - "
                            + params.getClass().getName());
        }
    }

    public String getAlgorithmName() {
        return "SM4";
    }

    public int getBlockSize() {
        return BLOCK_SIZE;
    }

    public int processBlock(byte[] in, int inOff, byte[] out, int outOff)
            throws DataLengthException, IllegalStateException {
        if (rk == null) {
            throw new IllegalStateException("SM4 not initialised");
        }

        if ((inOff + BLOCK_SIZE) > in.length) {
            throw new DataLengthException("input buffer too short");
        }

        if ((outOff + BLOCK_SIZE) > out.length) {
            throw new OutputLengthException("output buffer too short");
        }

        X[0] = Pack.bigEndianToInt(in, inOff);
        X[1] = Pack.bigEndianToInt(in, inOff + 4);
        X[2] = Pack.bigEndianToInt(in, inOff + 8);
        X[3] = Pack.bigEndianToInt(in, inOff + 12);

        int i;

        for (i = 0; i < 32; i += 4) {
            X[0] = F0(X, rk[i]);
            X[1] = F1(X, rk[i + 1]);
            X[2] = F2(X, rk[i + 2]);
            X[3] = F3(X, rk[i + 3]);
        }
        R(X, 0);

        Pack.intToBigEndian(X[0], out, outOff);
        Pack.intToBigEndian(X[1], out, outOff + 4);
        Pack.intToBigEndian(X[2], out, outOff + 8);
        Pack.intToBigEndian(X[3], out, outOff + 12);

        return 16;
    }

    public void reset() {

    }
}
